# Force equilibrium of a thick-walled pipe

1. Dec 15, 2011

### Arcturus82

Dear all,

I have a thick-walled pipe with an inner radius a and an outer radius b. The pipe is mounted to an outer rigid surrounding by N number of screws (applied at radius b) equally distributed around the pipe. Given an applied moment M on the inner radius a, I want to calculate the forces acting on the screws in order to verify that the screws are strong enough to keep the pipe in place.

Would the force F on each screw in such situation simply be F = M/(N*b) ? That is by using momentum equilibirum M = N*b*F around the center of the pipe. Or would the material deformation change this equilibrium in any way?

All the best

2. Dec 16, 2011

### gsal

"F on each screw"...in which direction? I presume that the F that appears in F=M/(N*b) is the F tangential to the outside of the pipe and right where the bolt contacts the pipe...in other words, this is friction force (if negligible deformation); it would be the same force that is trying to "bend" the bolt, but it is different from the force along the axis of the bolt...am I correct? Where, of course, Ffirction = Faxial-bolt X Friction-Coeff. ?

3. Dec 16, 2011